1. Field of the Invention
This invention relates to filtration systems, and more particularly relates to a support layer for a filter that maximizes fluid flow and throughput performance.
2. Description of the Related Art
Like gasoline, petrodiesel, or simply “diesel,” is typically produced through a refining and distillation process from crude petroleum oils. Diesel, however, contains about eighteen percent (18%) more energy per unit of volume than gasoline. This attribute, along with the greater efficiency of diesel engines, contributes to greater fuel economy in diesel vehicles.
On the other hand, diesel is about eighteen percent (18%) heavier than gasoline, which may cause problems for diesel vehicles not typical of gasoline vehicles. Particularly, operation in cold weather may cause diesel components to crystallize, thereby restricting fuel flow at the filters. While diesel additives may modify the size and shape of crystals that precipitate out of the fuel and/or delay their agglomeration at low temperatures to facilitate fuel throughput, high efficiency filters may have a negative effect on flow and throughput performance, particularly under cold weather conditions.
A typical fuel filter includes an outer layer that encapsulates an inner filtration media having one or more layers. This depth media-type filter generally exhibits high efficiency and capacity while effectively confining contaminants in the filter. Such a filter may be pleated to effectively increase filter capacity by maximizing available filtration surface area. Capacity may be further increased by reducing the thickness of the layers to enable tighter packed pleats. Such high capacity filters may result in restricted flow paths that are inadequate to enable cold flow, particularly in diesel systems.
Similarly, lube oil filters depend on adequate flow paths to ensure sufficient lubrication and low pressure drop. A certain amount of oil pressure is needed to circulate oil throughout the engine and maintain lubrication. Primary filters, or full-flow filters, must operate largely without restriction or oil will not flow into the engine during cold start-ups. Accordingly, full-flow filters allow passage of comparatively small contaminants to avoid flow restriction.
While a secondary filter may compensate for reduced efficiency by subjecting a small portion of normal oil flow to more efficient media to remove particulate contamination, the potential catastrophic effect of pressure drop is of paramount importance. Therefore, if blockage occurs in the primary filter, bypass valves open to enable oil to bypass the filter and return to the engine unfiltered. In this situation, lubrication with unfiltered oil is better than none at all.
To reduce flow restriction in fuel and lube oil filters, various support layers have been developed to attach to the filtration media to minimize pleat deformation and collapse. A metal screen, for example, may be implemented to provide increased rigidity to the filtration media while allowing for fluid flow thereacross. Similarly, a synthetic support layer, such as extruded polymer netting, may be implemented for increased structural support. These solutions, however, are often both costly to manufacture and difficult to implement.
Indeed, synthetic materials are inherently costly, rendering a support layer made therefrom likewise costly. Strands of metal used to create a support layer may snag or tangle in the filtration media, delaying production and increasing labor and resources necessary for proper manufacture.
Similarly, stray wire from metal screens may interfere with efficient production by getting caught in the filtration media. Metal screens may also dull equipment needed to size the support layer to appropriate dimensions. Further, metal screens are not incinerable and thereby complicate disposal of the filter after use.
Accordingly, what is needed is a filter media support layer that facilitates flow across a filter and that is inexpensive to manufacture. Beneficially, such a filter media support layer would facilitate filter disposal, enable effective small particle filtration and minimize pressure drop across the filter. Such a filter media support layer is disclosed and claimed herein.